Apache was crashing and in the error log was:
[warn] (OS 995)The I/O operation has been aborted because of either a thread exit or an application request. : winnt_accept: Asynchronous AcceptEx failed
The solution from here was increasing the max requests per child from 30 (I set this) to 10000.
Here is the section in `httpd.conf` that was edited.
# WinNT MPM # ThreadsPerChild: constant number of worker threads in the server process # MaxRequestsPerChild: maximum number of requests a server process servesThreadsPerChild 250 MaxRequestsPerChild 10000